9.38.1 Options

The following table lists all available s390 specific options:

-m31 | -m64

Select 31- or 64-bit ABI implying a word size of 32- or 64-bit.

These options are only available with the ELF object file format, and require that the necessary BFD support has been included (on a 31-bit platform you must add –enable-64-bit-bfd on the call to the configure script to enable 64-bit usage and use s390x as target platform).

-mesa | -mzarch

Select the architecture mode, either the Enterprise System Architecture (esa) mode or the z/Architecture mode (zarch).

The 64-bit instructions are only available with the z/Architecture mode. The combination of ‘-m64’ and ‘-mesa’ results in a warning message.

-march=CPU

This option specifies the target processor. The following processor names are recognized: g5 (or arch3), g6, z900 (or arch5), z990 (or arch6), z9-109, z9-ec (or arch7), z10 (or arch8), z196 (or arch9), zEC12 (or arch10) and z13 (or arch11).

Assembling an instruction that is not supported on the target processor results in an error message.

The processor names starting with arch refer to the edition number in the Principle of Operations manual. They can be used as alternate processor names and have been added for compatibility with the IBM XL compiler.

arch3, g5 and g6 cannot be used with the ‘-mzarch’ option since the z/Architecture mode is not supported on these processor levels.

There is no arch4 option supported. arch4 matches -march=arch5 -mesa.

-mregnames

Allow symbolic names for registers.

-mno-regnames

Do not allow symbolic names for registers.

-mwarn-areg-zero

Warn whenever the operand for a base or index register has been specified but evaluates to zero. This can indicate the misuse of general purpose register 0 as an address register.